The technology and features of the engine and platform look awesome! That quake demo is really slick (and seems it was released 2 years ago, would be nice to see some newer videos).

I'm worried about the pricing model though, you say it's free but on the developers page it mentions that Turbulenz is able to put any game developed with it on their site at any time they like. That doesn't sit right with me and perhaps you could improve that in some way to attract more developers to use the engine (I can see you're following in apples footsteps but you really don't have the market power apple has).

Also when I went to the main website it's telling me Javascript is disabled even though it's not. I'm running Chrome V22 (the latest beta) on Windows 7 and have whitelisted the domain in adblocker to no avail.